The present invention relates to an electromagnetic reed valve which includes a solenoid and, more particularly, to an electromagnetic reed valve in which the area of the opening of an outlet is varied rectilinearly in response to the amount of current supplied to the solenoid.
In a general electromagnetic reed valve, an outlet is opened in a valve chamber, to which working fluid is introduced. A reed valve body which is formed of an elastic plate is disposed at the valve chamber side in the outlet in a cantilever state where one end of the reed valve body is secured. The outlet of the valve chamber is opened by the reed valve body as required. On the other hand, a plunger which is moved to vary its stroke and hence its lifting amount in response to the amount of current applied to a solenoid is mounted at a lifter. The free end of the reed valve body is engaged by the lifter. In this manner, the outlet of the valve chamber is forcibly opened by deflecting the reed valve body.
In this structure of the electromagnetic reed valve, the area of the opening of the outlet of the valve chamber is proportional to the amount of the lift of the plunger. In the reed valve of this type, when the plunger is not lifted, the free end of the reed valve body is released from the lifter, and the outlet of the valve chamber is closed by means of the elasticity of the reed valve body itself.
However, when the outlet of the valve chamber is closed merely by the recoiling force of the elastic reed valve body as described above, the sealing force of the reed valve body for sealing the outlet of the valve chamber is small because the reed valve body of this type is normally formed of a thin elastic plate, and thus, it is inconvenient. One way to overcome such a difficulty is to impart a small amount of warp to the reed valve body in its counter-warp direction in order to provide an initial elastic force to the valve body, thereby increasing the sealing force of the valve body for the opening of the valve chamber. Since the initial elastic force caused by this warp is limited, however, the reliability of the sealing property of the valve body for the opening of the valve chamber is very low. One disadvantage of the conventional electromagnetic reed valve, then, is that the working fluid may leak from the outlet of the valve chamber. Particularly when dust or the like is interposed in the gap between the reed valve body and the seat surface at the periphery of the opening, the reed valve body will float from the seat surface of the opening, with the result that the leakage of the fluid becomes large and the reed valve accordingly loses its original performance.